Electron discharge tube



2 Sheets-Sheet 1 Filed April 7, 1955 Fig.1

gill/11111111111 1,111,111,, I 111 Fig. 2a

INVENTOR dull/n Kauai ATTORNEY Filed April 7, 1955 A. LAUER 2,937,309

ELECTRON DISCHARGE TUBE 2 Sheets-Sheet 2 Jnven/ar:

Unite ELECTRON DISCHARGE TUBE Anton Lauer, Ulm (Danube), Germany,assignor to Telefunken Gesellschaft fiir Drahtlose Telegraphie G.m.'b.H., Hannover, Germany This invention relates to the construction ofthe mounting of an electron discharge tube, such as a traveling wavetube, in which an electronic beam is guided and focused over a longerpath from a cathode to acollector electrode by means of a magnetic fieldwhich is parallel to the axis of the tube, said field being set up by apermanent or electromagnet.

The new mounting is provided in such manner that the magnetic field canbe aligned parallel with respect to the axis of the tube, i.e. this tubewhich is supported at its ends is adapted to be adjusted in its relationto the magnet energizing the magnetic field. 7

It is an object of the invention to provide a mounting of the tube sothat at one of its ends the tube can be moved or swung in alldirections, similar to a balland-socket joint action, while at its otherend the tube is radially adjustable.

It is another object of the invention to provide means at the radiallyadjustable mounting to lock the tube in any adjusted position.

These and other important objects and advantageous features of thepresent invention will be apparent from the following detaileddescription and drawings, appended thereto, wherein merely for thepurposes of disclosure non-limitative embodiments of the invention areset forth. I

Fig. 1 is a longitudinal section through a first embodiment of thetraveling wave amplifier tube accord ing to this invention.

-Fig. 2 shows a cross section through the tube of Fig. 1 at thecollector end of this tube.

Fig. 2a illustrates a cross section through a Fig. 2 along the line A-B.

Fig. 3 is a side view of another embodiment of the invention, shownpartially in section.

Fig. 4 illustrates a perspective view of a portion, i.e. the annularspring contact assembly, of the tube shown in Fig. 3, parts of theassembly being broken away t better show the inner structure.

Fig. 5 is a longitudinal section through a portion of a modification ofthe new device.

As shown in Fig. 1, within the evacuated envelope 1 there is provided adischarge system which comprises an electron gun 2 arranged inside acylindrical shield, a helical conductor or helix 3 and a collectorelectrode 4. The shield of the electron gun 2, together with two metalcylinders 5 and 6 and a metal member 7 surrounding the portion ofcollector electrode 4, serves as coupling means.

' The various parts of the tube are built into a grid comprising threeceramic rods 8, of which only two are visible in Figure 1. Inside thisgrid is positioned the helical conductor 3 between the couplingcylinders 5 and 6 in which the ceramic rods 9 are mounted. The ends ofsaid helical conductor 3 are passed through openings in 'the couplingcylinders 5 and 6, and are directly connected with the shieldsurrounding the elec- States Patent 0 in Figure 1.

ice

tron gun 2 and with the metal member 7 at the end of this traveling wavetube.

When the tube is in operation, there emanates from the beam generatingsystem a sharply focused electronic beam which traverses the helix ordelay line 3 and then impinges on the electron collector 4. To preventthis beam from spreading due to its space charge, there is provided, ina-manner known per se, a magnetic coil 19 surrounding the tube. In orderto avoid any bombardment of the helical conductor by electrons, themagnetic field energized by the coil 10 must be positioned parallel tothe axis of the helical conductor 3, since the electrons travel in thedirection of the lines of the magnetic field.

In order to avoid self-energization of such a tube, there is provided onthe ceramic rods 9 a damping means in form of strips 11 running in thelongitudinal direction of these rods. The ends of these strips are bentoutward, away from the helix 3, to assure reflection-less transmission,and these ends are thus diverted from the immediate field of the wavestraveling along the helix 3.

The high-frequency waves to be amplified are supplied via a hollow tubeconductor 12, while the amplified waves are taken 011 from a hollow tubeconductor 13. The two hollow tube conductors 12 and 13 are rigidlysecured to one another by means of a metal cylinder 27 ofnon-ferro-magnetic material which is spatially separated from thedischarge tube.

At the ends opposite to the connector sides, the two conductors areadjustable by means of tuning slides 14 and 15 for maximum energytransmission from the highfrequency line to the terminal of the helix.The distance of the slides 14 and 15 from the axis of the tube amountsto about A of the operating wave length. The operating voltage issupplied to the tube via the pin base fitting 16 and via a contact plate18 attached to the cooling ribs 17 of the collector electrode 4.Consequently, the operating voltages for the electron gun 2 are fed viathe pin base. The voltage for the helix is supplied via the metalcylinder 7, which is electrically connected to the wall of the hollowtube conductor 13 by means of an annuar spring contact member 19 whichwill be described in detail below.

This annular spring contact 19 serving as hearing or supportfor the tubepermits adjustments or movements of the tube in all directions at thecollector end of the tube. The pin base fitting 16 is connected to acupshaped member 20 with the aid of rivets, lugs, bolts or similarmeans. This cup-shaped member 20. engages with its flange 21 a'tubularsocket 22 which is attached to the hollow tube conductor 12 serving asinput.

Thecup-shaped metal member 20 is mounted on the threaded free end 2470fthe socket 22 by means of a cap screw 23. Therefore, the position ofthis part of the mounting can beradially adjusted upon loosening of thecap screw. By a radial shifting at this end, the

tube is swung about the center point of the universal bearing '19 at itscollector end 7. Since thereby the tube is angularly displaced from itsformer axis, the mounting 16 of the pin base fitting of the tube must bedesigned so as to be capable of taking up theresultant mechanicalstresses without damage to the tube. The usual pin base mountings forPico tubes available in the market satisfy these requirements adequatelyand permit a turning of the tube by several degrees without causingimpermissibly high stresses in the tube'socket' As a safety measure itis advisable to enclose the pin base fitting 16 with a protectivecasing42, such as is shown at left With'the' afore-described arrangementaccording to the invention apositioning of the magnetic field parallelto the helical conductor axis, which is necessary for the effectiveoperation of a tube, can be readily obtained in the following manner.After applying all required operating voltages, the cap screw 23 isslightly loosened and, by a radial displacement of the cup-shaped metalmember 20, adjustment is made to a position in which the helicalconductor carries a minimum of current. For this purpose, a measuringinstrument is suitably inserted in. the circuit of the helical conductor3. After. determining, this optimum position, the cap screw 23 istightened, so that a subsequent displacement of the tube from thisposition becomes impossible. Due to the universal adj-ustability of thetube assembly according to the invention, it becomes possible toadequately take care of any tolerances occurring in travelingwave tubeswith regard to the axis of the helical conductor, such tolerances beingunavoidable in the manufacture of these tubes. The device according tothe invention makes it possible to, reduce considerably the tolerancedemands as to the axial position of the helical conductor.

In practice, it is desirable to fix the axial position of the tube inthe socket. As shown in the embodiment of Fig. 2, an axial abutment isprovided, which can most simply be associated with the universallyturnable mounting member. In the example shown in Figure 2, a flange 25is provided on the cup-shaped metal member7 which is mounted universallyturnable in the contact ring 19 consisting of a helical spring havingits ends joined. This flange 25 engages an abutment on a tubular socket26 in a wobble-plate manner, said socket being attached to the hollowtube conductor 13 at the output end of the tube. The helical spring 19is lodged in an annular groove provided in the socket 26.

The inner diameter of this tubular socket 26 is made somewhat largerthan the outer diameter of the member 7 of the traveling wave tube, sothat the latter can be turned therein in all directions. Thus, theflange 25 of the metal part 7 may engage the wall of the tubular socket26 at a particular point thereof depending on the angular position ofthe tube. For example, in Figure 2, part 7 of the tube is shown at aslightly downward angle with regard to the axis of the mounting, thuscausing the member 7 to engage part 26 at a lower point near the outeredges of the two parts.

The universally adjustable mounting of the tube at its collector end isparticularly advantageous, since this permits at this collector end arelatively simple coupling structure comprising the metal parts 6 and 7which are connected to the wall of the hollow tube conductor 13.Therefore, any detuning caused during the axial adjust ment of the tubeat the places of contact with the input or output ends of the hollowtube conductors are less at the collector end than at the input end evenin case of larger displacements. It is necessary to keep the detuning toa minimum particularly at the collector end, since any reflected waveenergy might return to the tube and may cause undesired oscillations.This is not too critical at the input end, because waves reflected atthat place can, at worst, return to the source or to the controlgenerator. This source usually shuts oif the input end of the hollowtube conductor without reflection, whereby a wave reflected at the inputend travels to the source, or to the generator, without causing any disturbance.

Figure 3 illustrates another embodiment of this invention. The assemblycorresponds generally to that shown in Figure 1, Le. especially insimilarity of construction ofi'the mounting at the cathode end. The samereference numerals as in Fig. .1 are used for like parts in Fig. 3. Thetube mounting and the collector end of the traveling wave tube are shownin section.

Coupling cylinder 6 surrounding the helix 3, and the metal member 7surrounding the collector 4 are indicated in this sectional view. Thecollector 4 is mounted in the metal member 7 by means of a vitreous disk28. A

4 cooling head 17, having a plurality of cooling ribs, and a contactplate 18 are attached to the collector 4. 7

It is assumed in this example, for the sake of simplification, that theaxis of the helical conductor 3 coincides with the axis 29 of thetraveling wave tube amplifier. The metal member 7 supporting thecollector electrode 4 has a flange 25' similar to that shown in Figure2, said flange being. adapted to engage a socket 30 secured to thehollow tube conductor 13 at the output end in a wobble plate-likemanner.

The electric connection comprises a contact ring consisting of springelements 31. arranged annularly. The individual contact spring elements31 are shaped like lamellas, similar to those known as tulip contactsconventionally used in short-circuiting slides for high-frequency lines.Such a contact ring is shown in Figure 4 in perspective view.

The helical conductor 3 is connected similarly as in the constructionaccording to Figure 1, via the metal member 7 directly to the potentialof the magnet socket of the traveling wave tube amplifier, which isgrounded in the usual manner. To apply the operating voltage to thecollector electrode 4, the mounting assembly is enclosed in a tubularmetal cylinder 32 having an insulating member 33 covering the open endof this cylinder 32 housing the parts at the collector end of the tube.The insulating member 33 has an opening provided concentri cally withrespect to the axis of the traveling wave tube, a helical or compressionspring 34 being placed in this opening. The spring is adapted to bearagainst the contact plate 18 of the traveling wave tube collector 4. Alead for the operating voltage ispassed from the outside through theinsulating member 33 to be connected to the spring 34.

In each of the traveling wave tube amplifiers shown and described inthese examples, the mounting is designed in such a manner that the tubeis introduced from the output end of the amplifier into the pin basemounting at the input end of the amplifier. For this purpose, theinsulating member 33 in Figure 3 is held in the metal cylinder 32 bymeans of a bayonet-type fitting. Thus, by disconnecting this fitting itis possible to remove the insulating member 33 and to exchange the tubewith the aid of a tube puller. Instead of removing the insulating member33 it is possible to remove the metal casing 32. This has the advantagethat the tube can be removed by gripping it at the cooling head nowdirectly accessible, without the use of any tools.

It is expedient to provide the casing 32, just like cup member 20 at theinput end, with ventilating holes to remove the hot air and to admitcool air. Furthermore, it is possible to provide larger openings in thismember 32 and to direct a current of compressed .air through theopenings over the cooling ribs of the head 17 of. the collector.

The use of the type of universally adjustable mountings shown in theforegoing examples is also desirable, as losses in high-frequency energyare prevented because the all around engaging contact rings assure apractically perfect electric connection between the wall. of the hollowtube conductor 13 and the metal member 7 which is part of the couplingmeans, so that no high-frequency energy can escape via this mountingmember.

Figure 5 shows another exampleof a radially adjustable mounting. It isdesigned for application to the cathode end of a traveling wave tube.The pin base fitting 16 is fastened to a metal plate 35. This metalplate is provided with. relatively large holes 36 and '37 through whichbolts are passed to be threaded into the tubular member 22 which issecured to a wall 40 of the hollow tube conductor 12 at the input of thetube.

To avoid the loss of high-frequency energy across the gap existingbetween the coupling cylinder 6 and the inner wall of the member 22, aso-called M4 choke is provided in form of an annular gap or slot 41 cutor The proper adjustment of the tube .wtih respect to the position ofthe magnetic field is obtained in the following manner. After looseningthe bolts 38 and 39, the pin base fitting together with the plate 35 isradially displaced just as in the embodiment shown in Figure l, andafter determination of the optimum tube position the bolts 38 and 39 aretightened, thus locking the plate 35 rigidly in its position.

Thus, in the construction according to the invention, the tube ismounted in ball-and-socket joint fashion at one end, while the mountingat the other tube end is designed to permit radial adjustments. Theabutment in the other embodiments of the invention is a flange and theengagement in the embodiment of Fig. 5 may likewise take place at asingle place or point which can be provided at the input end of thetube. In the example, according to Figure l, the pin base mounting 16serves also as axial abutment for the tube. This is made possible byproviding the hollow tube conductors in such a manner that, withcomplete insertion of the pin socket of the tube into the pin basefitting 16, the planes of the metal members 2, 5, 6 and 7 are in aposition required for a transmission without reflection.

Although in accordance with the provisions of the patent statutes thisinvention is described as embodied in concrete forms and the principleof the invention has been explained together with the best modes inwhich.

1. In a travelling wave system including an electron discharge tubehaving an elongated envelope having at one end an electron emissivesource to emit an electron beam and having at the other end of theenvelope a collector electrode to collect the electrons of said beam,

said source and said collector electrode having a common axistherebetween, and said system including wave guide means having anenvelope-receiving cylindrical portion located between mutually spacedhollow wave input and output conductors respectively having openings forreceiving the source end and the collector end of the tube, and saidsystem including magnet means secured in fixed relation around saidcylindrical portion and setting up a magnetic field therewithin to focussaid electron beam, said field having an axis correspondingsubstantially with the axis of the cylindrical portion, improved supportmeans for positioning the tube in the cylindrical portion of the waveguide means comprising an annular bearing member on said tube axiallyadjacent to and precisely centered around the collector electrode;socket means attached to said output conductor at its opening andcoaxial with said cylindrical portion and having annular meanssurrounding said bearing member and maintaining it centered on the axisof the field; and mounting means attached to said input conductor at itsopening and having adjustable means gripping said source end of saidtube and being adjustably displaceable transversely of the axis of thefield, whereby the collector electrode is supported on the axis of thefield by said annular means and whereby said common axis can be orientedprecisely parallel with the axis of the field by said adjustable means.

2. In a system as set forth in claim 1, sad annular means in the socketcomprising an annular series of spring means maintaining the bearingmember on said tube sub-- stantially centered on the axis of the fieldwhile permitting tilting displacements of the member through smallangles.

3. In a system as set forth in claim 2, said bearing member on the tubeincluding at its outer end an outwardly extending flange adapted toengage the outer end of the socket and serving as an abutment to limitthe axially inward penetration of the tube into the wave guide means. 1

4. In asystem as set forth in claim 3, said collector electrodeextending beyond the envelope adjacent said flange; a casing coveringthe socket and enclosing the collector electrode; and a compressionspring supported in the casing by insulation means and compressedagainst the collector electrode, the spring maintaining the flange inengagement With thesocket and the spring serving as an electricalconnector for the collector electrode.

5. In a system as set forth in claim 2, said spring means comprising ahelical wire spring having its ends connected to form a ring, and saidsocket having an internal annular groove receiving the wire spring andmaintaining it in circumferential contact with said bearing member onthe tube.

6. In a system as set forth in claim 2, said spring means comprising anannular series of spring fingers disposed around and extending inwardlyof said socket to circumferentially contact the bearing member on thetube.

7. In a system as set forth in claim 1, clamp means on said mountingmeans at the input wave guide conductor and operative upon saidadjustable means for maintaining the latter in adjusted positiontransversely of the axis of the field.

8. In a system as set forth in claim 7, said input conductor having athreaded socket connected thereto around the opening; a cup covering thesource end of the tube and'screw means for securing the cup to thethreaded socket in adjusted position.

9. In a system as set forth in claim 7, said source end of the tubehaving connector pins extending thereto-rm, and said mounting meansincluding a plug base engaging said pins; a threaded socket connected tothe input conductor of the wave guide means at the opening therein; andscrew means for securing the base to the threaded socket in the desiredposition of adjustment.

References Cited in the file of this patent UNITED STATES PATENTS2,664,514 Reiches et al Dec. 29, 1953 2,666,160 Bowie Jan. 12, 19542,701,321 Rich Feb. 1, 1955 2,717,324 Hall Sept. 6, 1955 2,774,006 Fieldet a1. Dec. 11, 1956

